Can someone pleae explain how they were able to figure out the mRNA bands on the

Question

Can someone pleae explain how they were able to figure out the mRNA bands on the gel diagram based off the 6 strains above. I'm really confused on how to approach this. Any break down of of mRNA band for each strain would be really helpful!

6. You have a wild type strain of E. coli (strain a) and 5 strains that contain mutations in the lac operon (strains b- The genotypes for these strains are: Strain a: lacl* O* Z Y* Strain b: lacI O ZY Strain. c: lacI O Y Strain d: lacI O z Ydr Strain e: F" lacl OEZ Y lacI O Z Y Strain f F lacl' O Z Y lacI' O' Z Y Two kinds of lacz and lacY mutant alleles are studied. Both lacz and lacz lack Bgal activity (a func protein is not made). The lacz allele tional is a point mutation that causes a missense mutation in the lacz gene. The lacz allele is a deletion mutation that is missing 2 kbof lacz coding sequence. Both lacY and lac lack permease activity (a functional protein is not made). The lacY allele is a point mutation that causes a missense mutation in the lacY gene. The lacY allele is a deletion mutation that is missing 1 kb of lacY coding sequence. You grow the six strains in the presence or absence of inducer (PTG) and collect mRNA. which is run on a gel for Northern analysis using a radioactive DNA probe from the lacA gene. The wild type lac operon mRNA is 5 kb long. For all six strains (a-f) under inducing or non-inducing conditions, draw in the gel diagram where the expected mRNA bands would be. Kilobase (kb) size markers are shown to the left of the gel. Reminder: The lac operon has a polycistronic mRNA that contains three genes; lacz, lacY and lacA. nducer

Explanation / Answer

SAccording to the gel diagram shown the band sizes will be as follows:

Strain a: 5kb

Strain b : Both will be 5 kb

Strain c : Both will be 2 kb

Strain d : 4 kb

Strain e; 4 kb and 3 kb

strain f : 4 kb and 3 kb

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